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Solved Incoming calls failing with a 406 error code

Discussion in '3CX Phone System - General' started by MattG, Aug 19, 2017.

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  1. MattG

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    G'day!

    We're just starting experiencing an odd problem; for only a few of our extensions, calls to them are failing with error code 406. I haven't been able to identify any common reason why they'd be failing, yet other extensions would work fine. It occurs when the extension is dialed directly from another 3CX user, or when they are dialed from an outside line.

    I'm seeing the following in the logs on a failed call:
    Code:
    08/18/2017 5:24:53 PM - Call to T:Extn:5034@[Dev:sip:5034@192.168.1.22:50195;transport=TCP;rinstance=1-5671967b34114fb19534e30ad6373e6f;ob] from L:1733.1[Extn:5025] failed, cause: Cause: 406 Not Acceptable/INVITE from 127.0.0.1:5080
    08/18/2017 5:24:53 PM - [CM503003]: Call(C:1733): Call to <sip:5034@primary-intel.north.3cx.us:5060> has failed; Cause: 406 Not Acceptable/INVITE from 127.0.0.1:5080
    I've captured a packet trace to compare a successful call against an unsuccessful call, but I'm not seeing anything that's different. 406 tends to mean there's a problem with the method in the SIP message header, correct?

    Any insight on where to investigate next would be greatly appreciated. Any further details that I can provide please let me know.

    Thanks!
    -Matt
     
  2. lneblett

    lneblett Well-Known Member

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    This is generally an indication that there is something incompatible between the two devices that precludes one from being able to fulfill the other's request. In your case, you can check to see if it is just one phone that becomes a common thread when calls fail. I question the use of the loopback address (127.0.0.1) being used as shown in your post. As this is not an explicit address that is resolvable by anything other than the owning device. I am uncertain as to its validity.
     
  3. YiannisH_3CX

    YiannisH_3CX Support Team
    Staff Member 3CX Support

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    Hello @MattG

    What are the devices in question? Are they both 3CX clients? One of them is as it is using the tunnel. Is the other also remote? Unfortunately there are not a lot of information here to identify the cause. I will send you a p.m and ask for some files so we can identify the issue.
     
  4. YiannisH_3CX

    YiannisH_3CX Support Team
    Staff Member 3CX Support

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    The issue was that the option "RTP Mode" under extension settings was set to secure only and the extensions were using the tunnel. As this is not a supported configuration for extensions using the tunnel once the RTP Mode was set to normal and the clients were re-provisioned the issue went away.
     
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